1. Field of the Invention
Embodiments are related to image sensors, computer readable descriptions of image sensors, and methods for making mage sensors, and more particularly to such embodiments of CMOS image sensors.
2. Descriptive of Relative Art
The active pixel sensor is used in CMOS based imager arrays for a variety of applications. The sensor consists of an array of pixels (rows×columns) with the associated active circuitry on the same chip. Each pixel contains a photosensitive device that senses the incoming light and generates a ΔV difference on a floating node. The readout is accomplished by selecting a row of pixels and reading out each column, either column by column or all columns at the same time. The XY addressable APS is designed for CMOS technology with minor modifications to the process for the pixel while maintaining low-power and lower cost features compared to the CCD technology. Another main advantage of using CMOS process is to have the pixel array with the associated active circuitry on the same chip and save area and cost. Despite all of the benefits of using the CMOS process, the picture quality of the CCD image sensors is still superior to the picture quality of the CMOS APS. One of the main reasons for this difference is that the CMOS process is not suitable to designing a good pixel element, unlike the CCD process which is designed specifically to build pixel elements that result in a high quality picture. Another limitation of the CMOS process is that the operating voltages are low and not flexible as in the CCD technology.